Recoil check and barrel accelerator for automatic weapons



Nov. Z1, 1944. s. G. GREEN RECOIL CHECK AND BARREL ACCELERATOR FOR AUTOMATIC WEAPONS Filed Nov. 2, 1939 I Att :IY-nays. I

Patented Nov. 21, 1944 RECOL CHECK AND BARREL ACCEERATOR y FOR AUTOMATIC WEAPONS Samuel G. Green, Gray, Ga. I Application November 2, 1939, Serial No. 302,553

(Granted under the act of March- 3,y 1883, as amended April 30, 1928; 370 0. G. 757) 9 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a recoil check and barrel accelerator for machine guns and similar automatic weapons of the moving barrel type.

The purpose of this invention is to provide a recoil and barrel accelerator for barrels of the recoiling type which is especially adapted to perform its normal function independently of the guide bearing for the muzzle end of the barrel.

In the prior art, barrel accelerators have been used in conjunction with recoiling barrels wherein the guide bearing for the muzzle end of the barrel formed an integral part of a accelerator chamber, this arrangement, however, presents serious disadvantages due to the fouling of the barrel portion exposed to the gases in the acceleration chamber with consequent seizure of the barrel by the muzzle guide bearing and accompanying inoperation of the weapon. 'I'his disadvanfage may not be eliminated by increasing the It is an object of this invention to provide a,

barrel accelerator organized to form a guide bearing for the muzzle end of the barrel that will not be subjected to the corrosive and fouling effect of the gases collected in the acceleration chamber.

It is a further object of the invention to temporarily conne the gases of each explosion in an acceleration chamber and utilize them to accelerate the normal recoil of the barrel through a piston effect upon the muzzle end of the barrel without likelihood of seizure of the muzzle of the barrel by the Walls of the acceleration chamber through fouling.

It is still a further object of the invention to increase the energy of recoil of the barrel byfunetionally increasing the cross sectional area of the muzzle of the barrel acted upon by the gases collected in the acceleration chamber.

A still further object of the invention is to emthe heating and fouling effect of gases trapped by restricted discharge openings.

opening rearwardly and forwardly of the boosting chamber to eliminate pre-ignition and flash of unburned gases or other combustibles and to, avoid Still another object is to provide a barrel bearing with minimum bearing contact; such as a needle point or spline bearing, to aid in avoiding heat transfer and consequent binding of the barrel by expansion.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawing in which:

Fig. 1 is a view in longitudinal section of the recoil check and barrel accelerator of this invention 'attached to the muzzle of an automatic weapon of the recoiling barrel type.

Fig, 2 is a section taken on the line 2-2 of Fig. 1.

Fig. 3 is a section taken on the line 3 3 of Fig. 1.

Fig. 4 is a longitudinal sectional view of the muzzle portion of a modified barrel showing how a barrel may be formed to be received in direct bearing relation to the muzzle bearing.

Referring now to the drawing by characters of reference and more particularly to Fig. 1 there is shown the muzzle end of a recoiling barrel I0 disposed within a barrel jacket II as is well understood in the art.

A cylindrical barrel guide sleeve I2 of suitable heat resistant substance provided with an inwardly directed flange I3 at its rear end and an interiorly threaded reduced bore I4 at its forward end is sleeved over the muzzle of the barrel I0 with the iiange I3 engaging the exterior of the barrel and the reduced threaded bore I4 secured to the barrel through inteitnreaded engagement with exterior threads I5 on the muzzle end of the barrel. In this manner a gas sealed joint is effected between the muzzle of the barrel and the sleeve. The cylindrical portion of the guide sleeve I2 is disposed in non-contacting relation with the barrel whereby conduction of heat between the guide sleeve and barrel is reduced to a minimum. rl'he exterior forward end of the sleeve I2 is of reduced diameter as indicated at I6 for a purpose made apparent hereinafter.

While it is preferable to use a guide sleeve as ex- ,plamed it will of course be understood that the barrel itself may be used as the guide surface; in

Awhich case the sleeve I2 shown could be considered an integral part of the barrel functionally, and the muzzle portion of the barrel I would Abe formed as shown in Fig, 4 to be directly received by the bearing I9 hereafter described in greater detail.

A housing for the acceleration and recoil check gas chambers comprising a generally cylindrical tubular member I'l is secured to the muzzle end of the jacket Il in any suitable manner. In the form of the invention disclosed the rear portion of the member Il is inserted within the muzzle end of the jacket Il to a position where its rear end is in substantial registration with the flange I3 of sleeve I2 and is secured to the jacket as by the threads I8, although it will of course be obvious that any conventional locking means may be employed to eiect the desired interlocked relation between the jacket II and member I1. Adjacent the rear end portion of the member I'I an interiorly disposed guide bearing I8 is provided to slidably receiver the cylindrical bearing portion of the guide sleeve I2 in bearing and guiding relation throughout the positions of the barrel between battery and recoil.

Due to the relationship of the barrel guide bearing to the acceleration gas chamber herein subsequently described the guide bearing I9 may be relieved of full bearing engagement with the barrel guide sleeve I2 as indicated at 28 in Fig. 2 in order to reduce the friction between the guide sleeve and bearing to the least practical minimum, and tc prevent vthe trapping of any gases of combustion that would cause fouling of the bearing surface.

Intermediate its rear end and median portion the member I1 is formed to provide a plurality of radial circuinferentially spaced gas emission ports 2| so disposed as to normally be covered by the barrel guide sleeve I2l in and from the battery position of the barrel Il) to a predetermined recoil position of the barrel. Conveniently the ports 2l may be formed in a section of member Il of exteriorly increased radial section to facilitate the provision of an annular shoulder or abutment 22 adapted to abut the muzzle end of jacket II for the purpose of properly positioning the member II Within the jacket II during assembly thereon as above described and retaining the member within the jacket against breechwise movement. A second annular shoulder, or abutment 23 is also formed forwardly of the shoulder 22 for positioning a deilection disk to be later described. l

The barrel recoil acceleration gas chamber 24 is formed by the muzzle end or face of the barrel I0 and sleeve I2, a cylindrical tubular element or ring 25 inserted within the member I'I and a centrally bored cup-shaped member 25 also inserted within member Il with its concavity confronting the muzzle of the barrel. The element 25 is; made of high heat resistant substance capable of retaining a substantial percentage of its cold hardness whenv subjected to high temperature, such for example as Stellite, and is inserted within member I1 in abutting engagement with an interiorly disposed annular shoulder 21' in such manner as to encompass the cylindrical portion AI8 of sleeve I2 in the battery position of the barrel and during a predetermined recoil travel of Vthe barrel. Preferably the clearance 28 between the sleeve portion I6 of sleeve I2 and ring 25 is substanitally four times as great as the clearance between the bearing surfaces ofsleeve I2 and guide bearing I9. The comparatively great clearance between the sleeve and ring 25 in conjunction with the high polish maintained by the Stellite ring will be sufficient to by-passfany unburned particles carried by the gasesl of explosion into the acceleration chamber 24 past the sleeve through the clearance 28 to atmosphere by way of ports 2| without any tendency of the particles to bind between the sleeve and ring in the clearance 28. While the clearance 28 would be im practical where, as in the prior art the ring 25 has also served as a guide bearing for the barrel, it is admirably adapted to the organization of the accelerator of this invention and although the clearance 28 is suicient to permit the exhaust of the heavy particles carried in the gases of explosion without tendency of seizure of sleeve I2 by the ring 25 the clearance is suiciently small to throttle the gas that escapes from the acceleration chamber 24 and thereby retard reduction of pressure in the chamber 24 until the gas has imparted a predetermined amount of energy to the barrel for t'ne purpose of accelerating its recoil. The increased clearance 28 is offset by the'increase of the area of the barrel functionally effected by the forward end 29 of sleeve I2v against which the gas expands as well as the end of the barrel to drive the barrel in recoil after the manner in which gas acts on a piston in an internal combustion engine. To insure against any fouling collecting on the sleeve portion I6 the interior of ring 25 is formed with one or more clearance grooves 38 which operate in a well known manner. Although the invention as shown embodies a separate ring 25 as preferable because'of the ease of replacemenait will of course be understood that member I1 or cup 26 may be formed to include the ring 25 if desired.

As shown in the drawing the base 3I of the cup 23 is formed to abut the forward end of the ring 25 in substantially sealed relation and the disc is provided with an axial passage 32 disposed in prolongation with the bore of the barrel to form a projectile passage.

Forwardly of the disc 28 the member Il is prof vided with a plurality of circumferentially spaced v exhaust ports 33 of generally rectangular configuration having forwardly and inwardly inclined end defining walls. The forward face of the cup 23 is cut away inwardly from its periphery to form an annular seat 34 and a tubular insert 35 formed with ports 36 of the same configuration as the ports 33 and adapted to register therewith is inserted within the member I1 in abutting relation with the seat 34.

The recoil check gas chamber 31 is formed by the cup 26, insert 35 and an end closure plug 38. As shown the plug 38 is axially bored at 39 to` form a projectile passage and is provided with a conical concavity 40 on its inner face generallyl parallel with the outer conical face oi cup 28. The peripheral portion of the inner end of the plug 38 is cut away to form an annular shoulder 4I adapted to abut theV outer end of insert 35 and the plug is secured to the member I1 through interthreaded engagement or in other suitable manner as indicated at 4t with shoulder 4I abutting the outer end of insert 35 to retain the elements 25, 26 and 35 in proper position within member l1. The plug 38 is locked in prop er interthreaded relation with member l1 by a lock screw 42 or similar expedient. The spacing of plug 38 from cup 26 is so chosen as to permit discharge of the gases from chamber 3l through the parts 38 and 33 at relatively low velocity. In

Vrecoil direction', which area in the. present case is designed tobe approximately?? times the area of the bore'of `the weapon. This. gives an area upon which'the gases work ina counterrecoil di#- rection substantially. times the area used for similar'purpose in the prior art recoil checks of similar design for similar weapons. i

To prevent the gases exhausted from chamber 31 from interfering with the gunner in training the gun, a baiile check having a rearwardly diverging baiiie 43 and cylindrical interiorly threaded tubular portion 44 is exteriorly threaded on themember I1. A Spanner nut 45 may be threaded on member I1' to lock the baille member 43-44 in-position. Inaddition to controlling the deflectionof the gases to the rear the baffle check platelis adjustable to close the ports 36-33 for the' purpose of controlling therate of re of the Weapon. When the ports 36-33 are closedor partially closedthe pressure of the gases inchamber 31v are maintained higher for longer periods than when the lports are, fully openwith the result that thev pressures in chamber24 are also maintained higher for longer periods of time, due to :the back pressure'in .chamber 31, which will increase the working pressureof the gases acting on the barrel and barrel guide sleeve in a recoil l direction withconsequent acceleration inl recoil of these elements; fBy adjusting. the baie check plate over Athe portsv 362-.-33 the rate of fire may be'nicely'adjusted to compensate fdr' different Weight projectiles, vdifferent powder lots, etc.

.As more clearly shown in Fig. 'l the chamber 24 is agrelatively small hot chamber made of 'such size as to avoidl expansion ofthe gases of explosion 'discharging from the boreof the barrel `andpreferably-so formed` as to veffect compression of: the gases 'collecting therein so that the temvture andfeiectcombustion of unconsumed combustible particles carried by 'the gases'into the chamber. The gasesconned in chamber 24 will g act upon the end of barrel I0 and sleeve l2 to accelerate recoil of the barrel by imparting greater energy voi' recoil thereto. Because of the comparatively large clearance 28 between the ring 25 and sleeve portionl any unconsumed particles in .chamber .24 will beexhausted by the confined gases' in chamber 24 through the clearance 28 to atmosphere by way of ports 2|. vThe-'clearance 28 is made possible by provision of the'bearing I9 which accurately guides the muzzle of the barrel and eliminates all possibility of seizure. of the barrel by the ring 25. On the 4other hand the -use of a separate ring or gas check makes it possible to reduce the friction of the bearing I9 on sleeve l2 to a necessary minimum. The clearance grooves in ring 25 will clear any fouling that tends to accumulate on the sleeve portion I6. When the projectile enters the passage 39 the gases remaining in the bore and chamber 24 will enter chamber 31 and expand impinglng on the conical surface 4l) -of plug 38 and the forward defining walls of ports 36 and 33 transmitting a forward orcounterrecoil reaction to the member I1 and jacket Il which will counteract the recoil reaction of the weapon transmitted to the carriage or support for the weapon. As the size of the chamber 31 and working area of the chamber perature of the gases ywill beA maintained or even f Aincreased'to completelyburn unconsumed combustibles carried into the chamberby the gases in order that, ash, smoke,etc., will be reduced to a minimum. v

' While this invention'has been described in conl `nection` with an automatic weapon of the-recoil- Ving barrel type it is to befunderstood that the construction is adaptedl for use-witha gas `operated fixed barrel typeof gun with equal vfacility. by

simply cutting' the member I1 `oi forwardly of ythe ports 2l and `securing the barrel to the member l1 through threads cut in member I1 inthe area occupied'by ring 25.'A In this case the accelerationchamber may be eliminated ity desired.

In'the embodiment of the invention shown only one recoil chamber hasbeen` shown as it is not essential to resortgto the use of `multiple chambers where full advantage isjtakenof the area provided inv a single recoil check chamber of the' type described for checking the velocity of the gases, however, if desireda multiple series of recoil check chambers may be employed by substan-` tially duplicating the structure of'` the'sirigle chamber shown.`

As the recoil check gas chamber'is designed to reduce ther velocity vci the gases exhausted therefrom to a minimum the effect of the gases effective to check recoil is so coordinated as to utilize the Velocity head of the vgases entering the chamber in a maximum counterrecoil reaction .the velocity of the vgases exhausing through ports 36 and 33 is negligible in so far as the recoil reaction of the gases striking plate 43 is concerned. When it is desired to regulate the rate of fire of the gun it is only necessary toy screw the element 44--45 of the bale check forwardly to partially close the ports 36-7-33, This will cause the gases to remain in chamber 31 for av longer period of Atime at a higher pressure and through the back pressure so created likewise causes the gases in chamber 24 to remain at a higher pressure for a longer period of time with consequent greater lenergy of recoil being imparted to the barrel and -portion of the barrel, a guide sleeve surrounding the', muzzle portion of thebarrel in spaced relation andsecured to the muzzle end of the barrel in gas sealed relation, a guide bearing carried by the tubular member for the guide sleeve, a heat resistant ring in said tubular member encompassing the muzzle end of the guide sleeve in the battery position of the barrel, said ring and the muzzle end of the sleeve being so related as to provide a clearance therebetween substantially clearance, and a perforated conical cup in said tubular member with its perforation aligned with the bore of the barrel engaging the ring and forming a gas compression chamber in cooperation withthe ring and muzzle `encijofH thexbarrel and guide'sleeve. n I l `2. The structure of claimlwhereinthefguide bearing/is relieved' to reduce: frictionfandsaid ltsportion oflargestqdiameter, atheattresistant ring in said tubular memberencompassng j said `sleeve through aupartof its; reduced diametral portion, the diametercf said reducedfportion of the sleeve `and interior diameter of the ringibeing related to provide an annular clearance 1substanf tially greaterr than thevclearance between; the guidebearingz and'sleeve; gas exhaust ports in said tubular member communicating with the.l ring clearanceand` interposed betweenthering and guide bearing and means in said tubularvmember cooperating with the muzzlefend of-the barrel, sleeve and ring forming abarrel` accelerationggas chamber. l -5 'i s 1;`- j

4. The strueturegof claim 3 whereinsaidring is provided with one cry-more clearanceggrooves adapted to clear the reduced diameterportion of said sleeve'ofvanyioulmg deposited thereon. 5. In aweaponofA theclassdescribed; a barrel,`

a tubular member, means securing `theutubula'r member in operative relation to the muzzle of the y barrel, a plurality of circi1mierentiallj?y `sirnaced Iports formed in thetubular memberiorwardly of the muzzle-of the barrel,` additional portsrfonned in the tubular member rearwardly of the muzzle ofthe barrel, 4a removable closure plugghavng a projectile passagesecured in the forward; end of the tubular member anda bailleA check plate; comprising a cylindrical `portion and outwardly extendingbaiile Wall portion adjustably mounted on said tubular member intermediateysaidrst'rerr cited and additional ports by means .ofwitscylin-` 'Serieel' portion adapted to ,be adjusted tothrottle said rst recited ports. s .c

v6. In a weapon `of the character-described, a recciling barrel,` a jacket surrounding `said barrel and spaced therefrom, a tubular. guide member secured to the jacket and surroundingthe muzzle portion of the-gun barrels a .guide sleeve @carried byythe barrel,` a ring; in said tubularguideirnems ber surrounding then muzzle end ot the gun barrel when the `barrel is in battery positiomL said ring, the end` of the guide sleeve andren@` ofi` thefgun barrel being so related as to provide a:clearance pression .chamber-in cooperation with theyring endend cf;thefmuzz1e,-andgasexhaust ports in the `tubular :member connecting fwitli the `ring clearance and the gas compression chamber.

7. In a Weapon of `the tylzie havingva recalling barrel disposedv in z a spaced surrounding barrel jacket,` in(` combination; a, tubular: j bearing member secured `:to the jacket r` and` `surrounding :the

muzzleportion'of the` barrelfa guide sleeve cai;-i ried bythemuzzlei portion of the barrel, an abutmerit in the tubularmemberlauringin theltubiuar I member r engaging said` `abutment and Asurround-- ing the muzzle endof theflbarrelgsaid ring being spaced froml theend of the gunibarrel ,toby-Dass such solid;particles'as` rare 1 carried bythe `gases to provide a clearance. `between n the 'ring and barrel,

ports in` the*y tubular-:bearing :lmember communiey eating with said clearance; a conical `disk-having ayprcj ectiler passage: therethrough, i `said disk ene gaging the ring1 and cooperating with itandthe muzzle endvorthe barrelto formranfacceleration gas: chamber; a" tubular :insertl invsaid tubular bearingymember'engagingthe`gifcrward5face of y the comm disk,v registeringportsfffcrmed r in said tubular "member-and; insert, anda closure plug providodwith a projectilepassage secured inthe forward endjot thetubularinsert and engaging i the forwaraenc ofsaid 'insert :for holding: the

` substantialfV prolongation Awith; th

ring,r disk andxinsert in; assembled relationinY the tubular bearing; l member "and, @forming A a i recoil check gas chamber` int` cooperation with ;`said in sertanddsk. z i n 8. The invention cla-irrredl in claim, characterv izedin that thefclosureplug is provided with'rear walls substantially paralleliwith thefront faceof the; conicaldisk," and.y that? the ends `of the `registeringportson the tubularmember q and insert are provided; withfcrwarmyinclined surfaces r in faces of saiddiskandllp`1ug..` j j 9o Inxafweapon of.` the icharacterdescribed;L a barrelk jacket, a recoiling barrel abrupt-lyreduced ihfdiameter at its muzzle" end a substantial distance therefromformin`gr a shoulder adjacent saidgend, u a cupshaped :member having.` a cen`- tral proieetilei` openin'g; therethrough, thev said member in accopeiationcwith the barrel `forming an acceleration chamber,` said"memberbeing'pro` vided a Bange surrounding the reducedpor tion ofthe barrel whenltlrefsaid barrel is inbattery position, aclearance between said flange and barrel andl bypassing such solid,partic1es as are carried- `b'y theY gasesto prevent binding `of the barrc-:l/the'extreme` external diameter of the ange being commensurate :with `the barrel adjacent the-reduced portionlgftne rear end ,of the flange terminating shoitofgfthe shoulder wherebye conical sufr-` l Y f y CERTIEioATE 0E CORRECTION. Patent No. 2,562,996. November 21, 19th.

SAMUEL G. GREEN.

It 'is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page ll, second column, lines lh. to 16 inclusive, claim 7 for' "by-pass such solid particles as are carried by the gases to provide a clearance between the ring and barrel" read --provide a clearance between the ringand barrel to by-pass sachsolid particles as are carried by the gassen; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

signed and sealed this 50th day of January, A. n.119h5.

\ Leslie FrazerA (Seal) Acting Commissioner of Patents.

CERTIFICATE OE CORRECTION.

Patent No. 2,562,996. November 21, 19ML.

SAMUEL G. GREEN. It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page ll, second column, lines l1 to 16 inclusive, claim 7, forl "by-pass such solid particles as are carried by the gases t0 provide a clearance between the ring, and barrel" read --provide a clearance between the ring`and barrel to by-pass such solid particles as are carried by the gases; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the 'Patent Office.

signed and Sealed this 50m say of January, A. D. 19LL5.

Leslie Frazer v (Seal) Acting Commissioner of Patents. 

